This invention relates in general to the prevention of tension and common migraine headaches and temporal mandibular syndrome and, more specifically, to an intraoral device for preventing those conditions.
Many people suffer from recurring tension, or muscle contraction, headaches ranging from mild to severe. The severity of the headache often mimics the severity of classic migraine and can be diagnosed as "common migraine".
Tension is a muscular property. Muscles tense, or contract, to do work. When a muscle contracts statically and continually it will become painful. The intensity or degree of contraction and longevity of contraction will dictate the degree of discomfort.
The majority of the muscles that cover the human head (i.e., skull) are responsible for facial expression (raising eyebrows, smiling, etc.). Theses muscles are not strong enough to elicit the type of discomfort associated with headaches. There is an extremely powerful muscle, however, located on the side of the skull, extending from just behind the eye to just behind the ear. This muscle, the temporalis muscle, has one function to close (or "elevate") the lower jaw. When isometrically contracted, the temporalis muscle can exert a tremendous amount of static force. This isometric contraction can only occur when the posterior mandibular and maxillary teeth or dentures are in contact with each other.
The common tension headache in the temporal region is caused by moderate to severe inappropriate contraction of the temporalis muscles. Under usual and normal circumstances, the upper and lower teeth should rarely, if ever, come into pressure contact other than during normal chewing. The inappropriate muscular activity that clenches the upper and lower jaws together along with their associated dentition is called myofascial dysfunction.
Clenching is a motionless act, therefore, it is practically impossible to notice another person clenching. Additionally, clenching is most commonly done while the person is concentrating on another topic, or while dreaming, so that it is very difficult to have a self awareness of clenching.
As the muscular contraction condition of clenching continues, the muscles become fatigued and susceptible to spasm and cramping. The pain from a spasming or cramping temporalis muscle is quite severe and is usually diagnosed as "common" migraine. This type of migraine initiates as a severe headache that may last for two to three days. The muscle contraction headache patient, when seen by a physician, is usually treated with muscle relaxants and analgesics and may be referred to a physical therapist to treat the fatigued muscles. This treats the symptoms but does not address the cause.
These patients, when seen by a dentist, are commonly diagnosed as having temporal-mandibular joint syndrome. It is felt that a dysfunctional temporal-mandibular joint or an improper jaw-to-skull relationship causes the muscles to contract improperly, resulting in the headache. These patients are typically treated with a "jaw-repositioning" appliance, designed to relieve pressure on the distressed temporal-mandibular joint and allow a proper jaw-to-skull relationship. Typical of these are the orthotics or splints described by Norton in U.S. Pat. No. 4,671,766 and Sullivan in U.S. Pat. No. 4,519,386. The appliance, or splint, covers either the upper or lower posterior teeth and dictates jaw position by guiding the opposing jaw into "normal" position. Unfortunately, the upper and lower jaws are approximated by way of the splint, thus allowing the clenching to persist.
Thus, there is a continuing need for improved means and methods for preventing clenching of the teeth for prolonged periods to eliminate the resulting headaches and other related problems.